A pink, obligately themophilic (60 C), gram-negative, nonmotile, nonsporeforming, rod-shaped bacterium with a deoxyribonucleic acid base ratio of 64 to 65 mol% guanine plus cytosine has been repeatedly isolated from slightly alkaline, man-made and natural thermal aquatic environments. This bacterium (K-2 isolate) does not appear to have been described previously and it has been deposited with the American Type Culture Collection as an unidentified bacterium with the accession no. 27599.